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Corporate InformationResearch & Development

January 23, 2018

Report from Presenter

SocialSec 2017 was held in Melbourne, Australia. This international conference is an annual conference on security and privacy, and this year was co-hosted with two international conferences ISPEC 2017 and MONAMI 2017. 10 keynotes, 2 panel discussions and 85 presentations were held this time.

Fig. 1 A challenge of blockchain

The author gave a presentation titled "A Secure and Practical Signature Scheme for Blockchain Based on Biometrics."

Blockchain technology that has become a hot topic in recent years and Hitachi's original PBI (Public Biometrics Infrastructure) are integrated to realize a secure and convenient blockchain system. The blockchain is gaining considerable attention as the basis for realizing cryptocurrencies and smart contracts. However, in order to widely utilize the blockchain as a social infrastructure, there are various problems, one of which is the management of private keys for generating transactions. In the conventional blockchain system, since the private keys are managed on PCs or servers, there was a risk of leakage and loss of the private key. If the private key is leaked, it becomes possible for a third party to spoof using the leaked key and the asset is stolen. Also, if you lose your private key, you will not be able to create a new transaction, and you will lose your asset (Fig. 1).

Fig. 2 Public Biometrics Infrastructure

Fig. 3 Fuzzy key based signature scheme

In order to solve such a problem, we developed a technology to integrate blockchain and PBI (Fig. 2) which can generate a digital signature using biometric information such as finger vein as a private key. In this method, transactions are created based on digital signatures generated from biometric information. This makes it unnecessary to manage the private key, and it is possible to generate a blockchain transaction simply by holding your finger (Fig. 3). In this presentation, we implemented this method on the open source blockchain platform and confirmed that the transaction file size and processing time are at a practical level.

Fig. 4 Short-term key based signature scheme

However, in this method, every time a transaction is generated, it is necessary for a user to input the biometric information. Therefore, the use case where the IoT device automatically issues a transaction is not convenient and not practical. To solve this problem, we also developed short-term device certificate generation technology for automated transactions. In this method, we issue "short-term device certificate" valid only for a short term of time using user's biometric information and allow IoT device to automatically generate transaction for a certain term of time. By using this method, a blockchain system that achieves both security and convenience is realized (Fig. 4).

There were active questions in my presentation, and I was able to appeal the superiority of Hitachi's technology. In the future, we plan to increase versatility by adapting PBI to modality other than finger vein and large scale 1: N identification, and to promote commercialization to a wide range.

(By KAGA Yosuke)

Related Papers

  • Takahashi, K., Matsuda, T., Murakami, T., Hanaoka, G., Nishigaki, M.: A signature scheme with a fuzzy private key. ACNS 2015.
  • Matsuda, T., Takahashi, K., Murakami, T., Hanaoka, G.: Fuzzy signatures: Relaxing requirements and a new construction. ACNS2016.
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